Microsoft ties China's Storm-0940 to ARTEX AI-driven ConnectWise supply chain attack

Microsoft disclosed on October 21, 2026, that the China-state aligned threat actor Storm-0940 used an agentic AI penetration-testing framework called ARTEX to automate a supply chain compromise of ConnectWise's Cloud Backup service and reach customer Microsoft 365 environments through Microsoft Graph.

The password-spraying and intrusion activity tied to ConnectWise ran from October 10, 2026 through Microsoft's public report on October 21, 2026.

What happened

The actor has used these applications to access and exfiltrate email and other data through Microsoft Graph.

Storm-0940 initiated a widespread, but ultimately unsuccessful, password-spraying campaign immediately preceding the compromise of ConnectWise's Cloud Backup service.

Storm-0940's use of ARTEX accelerated the speed of compromised application abuse to authenticate to Microsoft 365 customer environments through applications that had already been granted access.

Storm-0940 used ARTEX to reach more than 2,250 tenants at 2,900 sign-in attempts per minute, a pace that leaves defenders with little time to detect and respond.

Impact

Several of these Storm-0940 ARTEX-driven attacks have resulted in the actor obtaining privileged access to an organization's cloud infrastructure, including multiple instances where the time from initial targeting to privileged access was less than 3 hours.

In some of these environments, the AI agents progressed beyond authentication to Microsoft Graph and directory operations, including reconnaissance, application credential modifications to establish persistence, and changes involving identities, groups, and privileged roles.

Microsoft did not say how many customers were compromised, adding that successful authentication doesn't necessarily indicate Storm-0940 accessed or stole data.

Microsoft said the activity conducted by the threat actor through the usage of ARTEX framework did not result from a compromise of or a vulnerability in Microsoft corporate systems, products, or services.

Response

ConnectWise published an initial advisory on October 16, 2026, and subsequently expanded its disclosures and containment guidance.

ConnectWise, which temporarily shut down services Saturday in the wake of the attacks, said it began restoring services in phases Wednesday.

Microsoft told customers to keep affected ConnectWise application connections disabled until ConnectWise provides formal restoration instructions.

Lessons for security leaders

Microsoft advised organizations to review every Microsoft 365 tenant where the affected applications are currently or were previously installed or authorized, even if the integration is no longer in use.

Microsoft also said the episode highlighted how a compromised third-party application with high privileges could provide access beyond its originally intended purpose.

Security leaders should treat OAuth application credentials and service principal sign-ins as high-value targets, since agentic AI tools can compress reconnaissance-to-persistence timelines from days to hours for any vendor integration with broad tenant permissions.